Because I have a skin on it, I am unsure of my DS's value. Is it higher or lower?

I am about to sell my original DS and I am not sure what the value is. The skin is a Heavy Vinyl Decal Skin (a href="http://cgi.ebay.com/Visible-Wind-Nintendo-DS-Skin-Skins_W0QQitemZ230109337969QQcategoryZ18807QQssPageNameZWDVWQQrdZ1QQcmdZViewItem#ebayphotohosting)" rel="nofollow"http://cgi.ebay.com/Visible-Wind-Nintend…/a . If it is heightened then I will leave the skin, and if not then I won't.